Q&A: What is the difference between cloth masks, surgical ones and FFPs?

Does single use really mean single use? And do visors work?

While Covid-19 restrictions have eased, face masks still have to be worn in certain settings. Conor Pope speaks to Dr Kim Roberts, Asst. Professor of Virology, TCD, who explains what face masks are best for preventing viral transmission.


With the pandemic almost behind us and most of the restrictions lifted, much of the focus has switched back to face masks. Masks remain a requirement in retail, schools and for certain cohorts of essential workers.

But not all masks are equal. Dr Kim Roberts is an associate professor of virology at Trinity College Dublin and, like most people, has been on a journey over the last two years when it comes to the wearing of masks.

In the early stages of the pandemic, she cautioned that care was needed before mask wearing became widespread. It was not that she doubted the efficacy of masks – they are common in her line of work – but she doubted our ability to use them correctly. Mishandling a face mask, she said, and taking it on and off, or touching it repeatedly with the virus on your hands was almost as dangerous as not wearing a mask at all.

But the world has come a long way over the course of the pandemic and masks have become widely available.

But what is the difference between a cloth mask, a surgical mask and an FFP, apart from the price? How often can we wear a face mask or does single use really mean single use? And are visors any use?

“I think one of the things that we need to acknowledge is that the debate about masks has changed a lot but also the virus itself has evolved. And as it has adapted to us, we’ve gone from one variant to another,” she says.

Covid-19 has become more infectious and “one consequence of that is that we can become infected if we’re exposed to smaller doses of the virus”. She says that at the start of the pandemic “there were limited supplies of certified personal protective equipment [PPE] and we were talking about large droplets”.


The size of the droplets matter when it comes to visors. The airflow changes when someone is wearing a visor.

“Instead of it coming directly to the person that you’re talking with, it goes out and down. Now the problem with that is...[the]transmission of this virus is not just about those large droplets, it’s also about the tiny droplets that hang in the air in a poorly ventilated indoor space. And this visor doesn’t protect against any of that, so you’re breathing in those airborne particles and you’re breathing out those airborne particles, and they’re going around the room. So a visor does not prevent airborne transmission.”

Cloth masks

The recommendation from the World Health Organisation (WHO) is that a cloth mask should have at least three layers of fabric. Many do not.

“The problem with these masks is not only that they have not got the layer of filtration...but there are all these gaps around it so the air is not being filtered particularly well [when you breathe out] and it is leaking out on all of these gappy places,” she says.

Cloth masks with three layers, and masks which come with a metal bar to pinch the nose and hold the mask in shape, are slightly better but still “not a certified mask”.

“The filtration effectiveness of this mask hasn’t been tested. It’s not classed as personal protective equipment,” she says.

Standard surgical masks

These are barrier masks that are “not designed to prevent you from breathing in [the] virus”, she says. The virus “is in tiny airborne particles in the air that you breathe out and they disperse through the air and they hang in the air. So in a poorly ventilated space, that virus can hang in the air for an hour or more. And we can then breathe in that virus. Omicron [is] more infectious so breathing in fewer virus particles can make you sick”.

FFP or N95 masks

FFP is the European standard while N95 is the US standard. “An FFP2 mask means that the material that it’s made from has a filtration capacity to filter out 94 per cent of particles,” says Dr Roberts.

The shape has been designed to better fit around the face and the material has been certified to filter out the particles as you breathe, “but you still have to think about the leaking around the face”.

The masks are not cheap and can cost in excess of €1 each. It is a lot to spend on a single-use product. But is it really single use?

“As consumers we are using it outside of how it’s been designed. A disposable FFP2 mask says it’s not for reuse but as consumers wearing these masks to go to the supermarket for short periods of time and not for a full day’s shift...you can take off your mask and store it in a plastic bag. And then use your hand sanitiser and save that mask for another use.”